The present invention relates broadly to transdermal administration of pharmaceutical compositions and, more particularly, pertains to a patch assembly and method for producing same which are highly effective and are capable of wide spread use for small customized dose formulations as well as for large volume dose formulations.
Much of the current research in drug delivery technology is aimed at developing formulations and devices that improve the therapeutic effectiveness of drugs over conventional means of administration by controlling the rate, time and place of release of drugs in the body. Conventional doses types include sublingual (under the tongue), oral (capsules, tablets, liquids), injectible, nasal and parenteral (suppository and non-oral) forms. While oral dosage forms comprise a substantial majority of all present dosage forms and offer ease of administration and low cost per use, they can suffer from inconvenient dosing intervals, side effects and reduced efficacy. Conventional dosage forms have disadvantages in certain patients including unpredictable blood levels, difficult or uncomfortable administration and poor compliance.
Controlled drug delivery systems have been introduced within the last decade to eliminate or reduce the limitations of conventional dosage forms. One type of controlled delivery is transdermal delivery, which involves delivery of a therapeutic agent through the skin for distribution within the body by circulation of the blood. Transdermal delivery can be compared to continuous, controlled intravenous delivery of a drug using the skin as a port of entry instead of an intravenous needle. The therapeutic agent passes through the outer layers of the skin, diffuses into the capillaries or tiny blood vessels in the skin and then is transported into the main circulatory system.
Transdermal patch devices which provide a controlled, continuous administration of a therapeutic agent through the skin are known as the art. Such devices, for example, are disclosed in U.S. Pat. Nos. 4,627,429; 4,784,857; 5,662,925; 5,788,983; and 6,113,940. Characteristically, these devices contain a therapeutic agent impermeable barrier layer which defines the outer surface of the device and a permeable skin attaching membrane, such as an adhesive layer, sealed to the barrier layer in such a way as to create a reservoir between them in which the therapeutic agent is placed. Although such devices may be satisfactory for their intended purpose, they have been found to be irritating to the wearer of the patch, provide minimized control of drug delivery through the skin, are slower to prepare, do not allow for customized formulation, are not easily produced and are not cost-effective.
Accordingly, there remains the need for a differently styled transdermal patch assembly which overcomes the drawbacks of the prior art and which is more easily and efficiently produced to address the individual needs of patients while also permitting high volume use.
In one aspect of the invention, a transdermal patch assembly includes a pressure sensitive carrier having a central opening, one side being provided with a clear liner thereon extending across the central opening, and an opposite side being provided with a first adhesive coating thereon, the carrier having a thickness such that when combined with the clear liner, a cell is defined by the walls of the central opening and an inwardly facing surface of the clear liner, the cell holding a pharmaceutical composition therein. The patch assembly also includes a pharmaceutical diffusing cover having an overlying side with an outer periphery attached by the first adhesive coating to an inner periphery of the carrier opposite side. The cover has an underlying side having a pair of opposed peripheral portions attached to a peelable release liner removably secured to an outer periphery of the carrier opposite side by the first adhesive coating. The carrier is preferably a foam substance while the clear liner is preferably a plastic material. Both the foam substance and the plastic material are impervious to the pharmaceutical composition. The pharmaceutical composition is comprised of a gel carrier and a drug. One side of the carrier is provided with a second adhesive coating for holding the clear liner in position. The cover is preferably comprised of tissue paper. The peripheral portions of the cover are generally semi-circular in shape and are provided with a third adhesive coating for attachment to the release liner. The release liner is impervious to the pharmaceutical composition. The release liner is preferably constructed of a clear plastic material. The release liner has an inner periphery which extends beyond the outer periphery of the carrier. The clear liner covers the entire one side of the carrier.
The invention further contemplates a method of assembling a transdermal patch comprising the steps of: a) providing at least one pressure sensitive carrier having a central opening, one side being provided with a clear liner thereon extending across the central opening, and an opposite side provided with a first adhesive coating thereon for removably holding a production liner thereon, the carrier including a cell defined by the walls of the central opening and an inwardly facing surface of the clear liner; b) providing at least one pharmaceutical diffusing cover having an overlying side with an outer periphery adapted to engage an inner periphery of the carrier when the production liner is removed from the carrier opposite side, and an underlying side having a pair of opposed peripheral portions removably attached to a peelable release liner adapted to removably engage an outer periphery of the carrier opposite side: c) removing the production liner from the carrier opposite side; d) depositing a pharmaceutical composition in the cell of the carrier; and e) affixing the outer periphery of the cover to the inner periphery of the carrier, and the peelable release liner to the outer periphery of the carrier. The step of providing at least one pressure sensitive carrier includes providing a perforated strip with a series of carriers. The step of providing at least one pharmaceutical diffusing cover includes providing a perforated strip with a series of covers. The method further contemplates a simultaneous operation of removing the production liner from the carrier opposite side, depositing a pharmaceutical composition in the cell of the carrier and affixing the outer periphery of the cover to the inner periphery of the carrier, and the peelable release liner to the outer periphery of the carrier.